On the basis of the existing mobile radio systems belonging to the so-called second generation, such as the familiar mobile radio system GSM (Global System for Mobile Communications), new mobile radio systems are being developed for the so-called third generation, such as the UMTS (Universal Mobile Telecommunications System) mobile radio system, which is being developed and standardized at present through a cooperation of the worldwide telecommunications industry. In comparison to previous mobile radio systems, especially to the GSM, the UMTS should be characterized by a higher and flexible transmission rate. A package-oriented exchange technology, particularly ATM, should also preferably be included in the UMTS. In contrast, service-oriented exchange technology is primarily used in the existing mobile radio systems.
In the article xe2x80x9cMobilfunk der dritten Generationxe2x80x9d [Mobile Radio of the Third Generation] by M. Kien and S. Gneiting, which was published in the journal xe2x80x9cFunkshouxe2x80x9d [Radio Show], volume 7/99, WEKA-Verlag, Poing, Germany, the authors write that the new mobile radio system UMTS should be constructed and developed as an addition to the existing mobile radio systems. This would not mean a simple coexistence of the different mobile radio systems. Rather the different generations of mobile radio systems should be linked so that one and the some wireless subscriber unit can be operated in the different mobile radio systems. Such a subscriber unit is known as a xe2x80x9cmulti-mode capablexe2x80x9d subscriber unit. Not only should it be possible to operate the unit in the different mobile radio systems, but it should also be possible to hand the unit over from one mobile radio system to another during operation, particularly during a conversation or while data is being transmitted.
The goal of the present invention is to propose a procedure and equipment through which different mobile radio systems can be connected together as simply as possible, and which will fulfill the technical requirements mentioned at the beginning.
This goal is achieved according to this invention by a procedure for data transmission between a first mobile services switching center of a first mobile radio system and a second mobile services switching center of a second mobile radio system, in which the mobile services switching centers are connected via an interface through which useful data are transmitted at a variable useful data transmission rate, in which the useful data are transmitted within data frameworks, which includes a definite pre-determined number of data fields, whereby at first, depending on the amount of useful data to be transmitted, at least one part of the data fields is first encoded with the useful data and afterwards the remaining part of the data fields is encoded with dummy bits. The invention is further directed to mobile services switching centers and interface switches implementing the procedure.
Accordingly, a procedure for data transmission between a first mobile services switching center of a first mobile radio system and a second mobile services switching center of a second mobile radio system is proposed, whereby the mobile services switching centers are connected by on interface, via which useful data are transmitted at a variable useful data transmission rate, in which the useful data are transmitted within data frameworks including a definite pre-determined number of data fields, whereby, depending on the amount of useful data to be transmitted, at least one part of the data fields is first encoded with the useful data and then the remaining part of the data fields is encoded with dummy bits.
Furthermore, a mobile services switching center is proposed for a mobile radio system with an interface switch, which exchanges the useful data with another mobile services switching center of another mobile radio system, in that the interface switch sends and receives the useful data at a variable useful data transmission rate within data frameworks, whereby each data framework includes a definite pre-determined number of data fields, of which, depending on the amount of useful data to be transmitted, at least one part is first encoded with useful data and then the remaining part is encoded with dummy bits.
The present invention also proposes an interface switch for a mobile services switching center of a mobile radio system which exchanges useful data with another mobile services switching center of another mobile radio system, in that the interface switch sends and receives the useful data at a variable useful data transmission rate within data frameworks, whereby each data framework includes a definite pre-determined number of data fields, of which, depending on the amount of useful data to be transmitted, at least one port is first encoded with useful data and the remaining part is then encoded with dummy bits.
Through the measures proposed in the present invention, the mobile services switching centers of the different mobile radio systems are able to exchange useful data at a variable useful data transmission rate, that is at a variable net transmission rote, however whereby data frameworks with a definite pre-determined number of data fields are used. On the other hand, a connection with a fixed gross transmission rate determined by the number of data fields is created between the mobile services switching centers. This connection can be switched using a service-oriented switching technology, whereby it is also possible to use simpler and mostly older mobile services switching centers. By filling the data fields either with the useful data to be transmitted or with dummy bits, the data framework is only generally filled with payload to the point necessary for the momentary useful data transmission rate. This produces a connection with a variable net transmission rate, which can be adjusted to a package-oriented technology at little expense. The present invention is especially well suited for handing over a wireless subscriber unit from one mobile radio system to another, especially when the hand over involves a change from a service-oriented technology to a package-oriented technology.
One especially advantageous embodiment of the invention results from the subordinate claims:
According to these claims, it is especially advantageous to combine at least two consecutive data frameworks, whereby a signal bit in the relevant data framework indicates whether it is the first or the second of the two data frameworks. This creates double or multiple frameworks with a larger number of writeable data fields, producing a greater range of variation for the net transmission rate.
Another particular advantage is created if, beginning with the first data field of the first data framework, the data fields of the combined data frameworks are successively encoded with the useful data to be transmitted, and if the remaining data fields are encoded with dummy bits when necessary, and if the display bits of the first data framework together with those of the second data framework indicate on address marking the position up to which the combined data frameworks ore encoded with useful data. Through these measures, the useful data are encoded in an interconnected data block, whose beginning is known and whose end is determined by the amount of useful data. In order to access the transmitted useful data, it is only necessary to mark the end of the data block with display bits.
Furthermore a particular advantage is created if a wireless subscriber unit being operated in the second mobile radio system is handed over to the first mobile radio system, in that the useful data sent and received by the wireless subscriber unit via the interface is transmitted transparently, whereby the display bits indicate those data fields which are encoded with the useful data to be transmitted and/or indicate those data fields which are encoded with dummy bits. These measures allow for a quick hand over from a system using service-oriented switching technology to a system using package-oriented switching technology.
Another advantage is created if a wireless subscriber unit operated in the second mobile radio system is handed over to one operated in the first mobile radio system, in that the useful data sent and received by the wireless subscriber unit via the interface are transmitted non-transparently and according to a data link protocol selected-from various data link protocols, and if control bits indicating the selected data link protocol with which the data fields of the data framework ore encoded with the useful data, ore input in the data framework. These measures allow for a quick hand over from a system using package-oriented switching technology to a system using service-oriented switching technology.